The instant invention is a hydraulically controlled transmission. Specifically, the instant invention is a hydraulically controlled two-speed transmission residing primarily within a rotatable wheel hub. Air or gas may be used to control the transmission instead of hydraulic oil if desired. The transmission includes a spindle which is affixed to the frame of a vehicle. An outer ring is affixed to the spindle such that the outer ring is stationary. The transmission provides for two speed reductions. Two planetary gear sets are employed to accomplish the two speed reductions. The transmission is suitable for use on agricultural vehicles and truck cranes and generally those machines that work off road and travel on road. It will be appreciated by those skilled in the art that the invention is not limited to transmissions residing primarily within a rotatable wheel hub.